Nodulation Trio inMedicago truncatula:Unveiling the Overlapping Roles of MtLYK2, MtLYK3, and MtLYK2bis

The perception of rhizobial nodulation factors (NF) by plant NF receptors is crucial for mediating legume nodulation. In Medicago truncatula nodulation, a proposed two-receptor model designates MtLYK3 as an entry receptor, while other LYK proteins, with unidentified functions, may serve as signaling receptors. Here, we generated the single, double, and triple mutants for M. truncatula MtLYK2, MtLYK3, and MtLYK2bis using CRISPR/Cas technology and examined their roles in nodulation. Our findings suggest that all three LYKs possess redundant functions in Medicago nodulation, with their distinct contributions attributed to varying transcription patterns.Our findings also suggest that a one-receptor model with multiple specificities that mediates both signaling and entry responses is more suitable in M. truncatula.